NASA: Even small meteor can wreak big havoc

While all eyes were on a 150-foot asteroid harmlessly skimming Earth's atmosphere Friday, it was upstaged by a surprise meteor a third its size that appeared out of nowhere and exploded in a fireball above the Ural mountains near Chelyabinsk, Russia.

It's the "out of nowhere" part that concerns some experts.

"We have confidence in our ability to predict the orbits of asteroids very precisely, but we have to know about them in order to do so," said Dan Mazanek, Near-Earth Object (NEO) technical lead at NASA Langley Research Center in Hampton. "With the vast majority of these small objects currently undetected, an incident like the Chelyabinsk event is by far the most likely future scenario.

"There are likely hundreds of thousands or even millions of near-Earth objects similar in size to the object that exploded over Russia last Friday. I think this Russian meteor will likely make scientists reconsider the size capable of destruction to people and infrastructure on the ground, once we get some data on its properties."

An asteroid is a small, rocky body locked in solar orbit. A meteor is a meteoroid, or chunk of space rock or debris, that falls into a planet's atmosphere. Pieces that strike the ground are called meteorites.

NASA estimates Friday's meteor was 55 feet across and weighed about 10,000 tons when it entered the atmosphere. By comparison, the asteroid called DA14 was 150 feet across and weighed 130,000 metric tons.

The meteor rocketed across the sky at about 19 miles per second, according to Russian scientists. The force of the explosion as it entered the atmosphere broke the space rock to bits, scattering meteorites over a vast, wintry landscape.

Shock waves shattered thousands of windows, caused $33 million worth of damage and injured nearly 1,200 people, according to reports.

On the same day, smaller objects also believed to be meteors exploded above Cuba and the San Francisco Bay Area, rattling windows and walls but causing no injuries, the Associated Press reported.

"Meteorites are not as uncommon as you think and can be found all over the earth," said Mazanek. "Of course there are types that are rarer than others, but many meteorites are hard to distinguish from terrestrial rocks unless you know where they fell."

This is why meteorites are more easily distinguished on ice fields such as those found in Antarctica, he said.

According to reports, residents in and around Chelyabinsk launched a "meteorite rush" over the weekend, collecting chunks of space rock to keep as souvenirs or to sell. Russian scientists have tested fragments and confirmed they are "chondrites," or stony meteorites.

A 26-foot hole discovered in the ice of nearby Lake Chebarkul is suspected to have been caused by a larger fragment. Mazanek called the hole a "great calling card" for impact.

Smaller meteor strikes occur five to 10 times a year, experts say, and most land in uninhabited areas. For every NEO already detected, scientists estimate 99 others remain undetected.

While the asteroid and meteors crossed Earth's path on the same day, Mazanek and other scientists say it was mere "cosmic coincidence."

The objects came from different directions and orbits and occurred too far apart to have been related, Mazanek said.